Essential to the development of a low carbon economy will be the advancement of building product and process to reduce the capital and whole lifecycle cost of low, zero and net-positive energy buildings to allow these structures to be realized at a greater rate. On the whole, the built environment is responsible for one of the largest fractions of global energy consumption and thus anthropomorphic climate change, a result of the greenhouse gas emissions from power generation. When one also considers the energy required to design, fabricate, transport and construct the materials necessary to bring new building stock online, keeping pace with the rapid trend towards urbanization, the importance of the built environment in the energy sustainability equation is clearly evident. Yet, while technologically feasible, the realization of carbon neutral buildings is encumbered by the perception of increased annualized costs for operation and a greater upfront investment. This paper will review the design case of the Masdar International Headquarters, the flagship building of the net-zero carbon emission Masdar city currently being developed within the Abu Dhabi Emirates. Specifically, how an integrated approach enabled by computer simulation early within the design process allowed for improvements in economy and efficiency, setting a model for future high performance buildings. The five-story, 89,040-square-meter office building will incorporate eleven sculpted glass environmental towers to promote natural ventilation and introduce daylight to the interior of the building. These towers will also serve as the structural support for one of the world’s largest building integrated photovoltaic arrays, sized to supply 103% of the building’s total annual energy requirements while protecting the building and roof garden from intense heat and solar gains. Moreover, by integration into a separate structural trellis system, clean energy can potentially be generated to offset construction requirements while dually shading workers below during the heat of the day. This, along with other key sustainability design strategies such as a solar powered central district cooling system, thermoactive foundation piling, underfloor air distribution, desiccant dehumidification, a nanotechnology enabled building envelope and smart grid enabled facilities management infrastructure will allow the Masdar Headquarters to reach carbon neutrality within a decade, allowing for the remaining century of its operation to serve as a platform for clean energy generation.
The successful widespread adoption of fuel cell systems is highly dependent upon the economics of the installation. This entails closely matching system capabilities with customer requirements. System sizing requires accurate predictions of building thermal and electrical loads. The TRNSYS-based building simulation model presented in this paper was developed to accurately integrate a fuel cell into the space heating, water heating, and cooling equipment in a building. The simulation tool determines water heating, space heating, and cooling loads for a single zone building on an hour-by-hour basis throughout the year using TMY2 weather data. It integrates empirical and theoretical state point models of the components of a fuel cell-based cogeneration and tri-generation system as well as baseline HVAC technologies. The key components include: hot water loops, stratified water tanks, boilers, furnaces, air conditioners, absorption chillers, space conditioning coils, heat rejection equipment, and ventilation controls. Various control options are incorporated to maintain setpoints, stage equipment, and limit power export. Renewable power systems such as PV and wind are also integrated into the model. The TRNSYS calculation engine iterates to find the state of the system for each hour. The simulation tool also includes post-processing capabilities to apply complex electric tariffs, organize annual simulation results, and manage multiple parametric runs. The tool has been developed to optimize the configuration of a fuel cell in a given building application and to complete numerous parametric runs to evaluate the economics of a system in different locations and building applications. This work was funded in part by the New York State Energy Research and Development Authority.
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